1. Field of the Invention
The present invention relates to a magnetic head, which is used in a floppy disc drive (a downwardly compatible high recording density FDD) having both a standard (i.e., low) recording density and a high recording density, or the like, and which is compatibly applicable to a plurality of recording media having respective recording densities different from each other.
2. Description of the Related Art
An example of a magnetic head used in a downwardly compatible high recording density FDD is shown in FIGS. 6 to 8.
A magnetic head 30 shown in FIGS. 6 to 8 is of a type bearing two magnetic cores 31 and 32 (for instance, a magnetic core of 120 MB type and a magnetic core of 2 MB type) having respective recording densities different from each other, and the magnetic cores 31 and 32 form respective closed magnetic circuits independent of each other. The magnetic cores 31 and 32 are inserted and positioned in slits 37 and 38 formed in a slider 35, and fastened with glass or the like. After a sliding surface of a magnetic recording medium is formed by machining such as cutting and polishing, coil windings 33 and 34 are applied on a window portion of the magnetic core respectively.
In addition, a conventional type of magnetic head without so-called compatibility is shown in FIGS. 9 and 10. The magnetic head shown in FIGS. 9 and 10 is of a so-called separated type as will be described later and used in an FDD for a standard recording density (a normal FDD). In this magnetic heads a read/write core 42 and an erasing core 43 are accommodated and held in an opening 41 formed in a substantially rectangular slider 40. A back yoke 44 is connected to the read/write core 42, the erasing core 43 and the slider 40. The back yoke 44 forms a closed magnetic circuit in association with the read/write core 42 and the erasing core 43, and supports the slider 40.
The back yoke 44 is generally comprised of a substantially rectangular back yoke body 45 which is a little larger than a slider 40, a first leg portion 46, a second leg portion 47 and a third leg portion 48 which are all standing upright in a line on one face of the back yoke body 45, and an outer circumference wall portion 49 standing upright on the outer circumference portion of the back yoke body 45 and connected to the slider 40.
The first leg portion 46 is connected to the read/write core 42 thereby forming a closed magnetic circuit with the read/write core 42. The third leg portion 48 is connected to the erasing core 42 thereby serving to form a closed magnetic circuit with the erasing core 42. The second leg portion 47 is connected to a joint portion of the read/write core 42 and the erasing core 43 thereby serving in common to form respective closed magnetic circuits with the read/write core 42 and the erasing core 43.
As mentioned above, since the back yoke body 45 is formed a little larger than the slider 40, a space 50, which is not covered by the slider 40, is formed on an upper surface of the outer circumference wall portion 49. A resin 51 is applied to this space 50 to fix the slider 40 and the back yoke 44 together.
A read/write coil 52 having three lead wires 52a, 52b and 52c is mounted on the first leg portion 46. An erasing coil 53 having two lead wires 53a and 53b is mounted on the third leg portion 48.
Two cut-outs 54a and 54b are formed on the outer circumference wall portion 49. Three lead wires 52a, 52b and 53c of the read/write coil 52 are let through the cut-out 54a to the outside, and two lead wires 53a and 53b of the erasing coil 53 are let through the cut-out 54b to the outside.
In the magnetic head shown in FIGS. 9 and 10, the resin 51 is applied to the space 50 of the upper surface of the outer circumference wall portion 49. It is difficult to control an amount of application, and the resin may be accidentally attached to the upper surface of the slider 40, or a poor adhesion may be caused due to an insufficient amount of resin.
Further, since the magnetic head shown in FIGS. 9 and 10 has one kind of recording density applicable to a recording medium and is not compatible, it is not convenient. Further, three lead wires 52a, 52b and 52c of the read/write coil 52 are let through one cut-out 54a and two lead wires 53a and 53b of the erasing coil 53 are let together let through one cut-out. This makes it happen that wires with respective different roles such as a starting end of coil or finishing end of coil are mistaken for each other when wiring. So, careful work is required thereby lowering workability and productivity.
The present invention has been made in light of the above circumstance, and an object thereof is to provide a magnetic head, which enables workability for coil termination to be increased, prevents mistake in wiring and which is compatibly applicable to recording media having respective recording densities different from each other.
According to a first aspect of the present invention, in a magnetic head comprising a slider which slides on a magnetic recording medium, and accommodates and holds a plurality of magnetic cores having respective gaps and having recording densities different from each other in a plurality of openings formed on a sliding side, respectively, and a back yoke which comprises a substantially plate-like back yoke body provided parallel to the slider, a plurality of inner pillars standing upright on the back yoke body and four walls standing upright on respective edges of the back yoke body and connected to the slider and which is connected to the magnetic cores thereby forming closed magnetic circuits, holds the slider, and includes a plurality of coils provided on the plurality of inner pillars provided corresponding to the plurality of magnetic cores, respectively, the four walls include cut-outs in number equal to or larger than number of lead wires of the plurality of coils.
According to a second aspect of the present invention, in the first aspect, at least three cut-outs are provided on each of the four walls.
According to a third aspect of the present invention, in the first or second aspect, the back yoke, the inner pillar and the walls are integrally molded using a soft magnetic material.
According to a fourth aspect of the present invention, in any one of the first to third aspects, at least two of the plurality of magnetic cores are for a standard recording density floppy disc drive and for a high recording density floppy disc drive, respectively.